This is a minor fix for Petra 0.99o that i wrote ages ago and uploaded to VOGONS for testing as some SB16 systems didn't work correctly, but i never managed to put anywhere else.

This is only relevant if you have sound issues with the game on DOS systems so i didn't want to make a full new release just for that. If i make a new "proper" release i'd like it to be based on the standalone Petra Engine but as that has some modifications from the engine the game comes with i'd need to convert it to that.

The code was already part of the engine source in Codeberg so i didn't update any code here.